ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus GmbHGöttingen, Germany10.5194/acp-11-2671-2011Impact of deep convection and dehydration on bromine loading in the upper troposphere and lower stratosphereAschmannJ.1SinnhuberB.-M.13ChipperfieldM. P.2HossainiR.21Institute of Environmental Physics, University of Bremen, Bremen, Germany2School of Earth and Environment, University of Leeds, Leeds, UK3now at: Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany2203201111626712687This work is licensed under a Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/This article is available from http://www.atmos-chem-phys.net/11/2671/2011/acp-11-2671-2011.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/2671/2011/acp-11-2671-2011.pdf

Stratospheric bromine loading due to very short-lived substances is
investigated with a three-dimensional chemical transport model over
a period of 21 years using meteorological input data from the European
Centre for Medium-Range Weather Forecasts ERA-Interim reanalysis from
1989 to the end of 2009. Within this framework we analyze the impact
of dehydration and deep convection on the amount of stratospheric
bromine using an idealized and a detailed full chemistry approach. We
model the two most important brominated short-lived substances,
bromoform (CHBr<sub>3</sub>) and dibromomethane (CH<sub>2</sub>Br<sub>2</sub>),
assuming a uniform convective detrainment mixing ratio of 1 part per trillion by
volume (pptv) for both species. The contribution of very short-lived
substances to stratospheric bromine varies drastically with the
applied dehydration mechanism and the associated scavenging of soluble
species ranging from 3.4 pptv in the idealized setup up to 5 pptv
using the full chemistry scheme. In the latter case virtually the
entire amount of bromine originating from very short-lived source
gases is able to reach the stratosphere thus rendering the impact of
dehydration and scavenging on inorganic bromine in the tropopause
insignificant. Furthermore, our long-term calculations show that the
mixing ratios of very short-lived substances are strongly correlated
to convective activity, i.e. intensified convection leads to higher
amounts of very short-lived substances in the upper troposphere/lower
stratosphere especially under extreme conditions like El Niño
seasons. However, this does not apply to the inorganic brominated
product gases whose concentrations are anti-correlated to convective
activity mainly due to convective dilution and possible scavenging,
depending on the applied approach.